Welcome to this page, which deals mostly with physics and science fiction.
I'm Johan Wevers. I hope that you find the information presented here of value
to you.

I am a graduate in applied physics at the Eindhoven University of Technology.
For those interested, my graduation report, that
dealt with the experimental and numerical study of a hydrogen plasma is also
available here, also in pdf form.

This document is a LaTeX file of 108 pages which contains a lot of equations
in physics. It is written at advanced undergraduate/postgraduate level. It is
intended to be a short reference for anyone who works with physics and often
needs to look up equations. A list of recent changes
is available.

9.1 PGP

PGP, short for Pretty Good Privacy, is a program whose primary use is
to encrypt email by using a special algorithm that does not require a safe
channel to exchange keys or passwords between people. It does so by encrypting
messages with a public key, who can only be decrypted by the owner of
the matching secret key. The public key can be given away to anyone
interested, the secret key should (as the name suggests) be kept secret.

Because the time it takes to derive the secret key from the public key is much
longer than the estimated age of the universe this is pretty safe. But for this
type of products it is best to know all possible weaknesses, after all you'd be
better safe than sorry. Therefore I recommend reading the documentation and look
at the the PGP
attack FAQ: although the document is a bit outdated and does only handle issues
with pgp 2.x, it shows how to think about security related to encryption.

PGP is originally written by Philip Zimmermann in 1991.

9.2 Standardization?

Due to the introduction of PGP 5, 6 and later,
which are very platform dependant and deleberately made incompatible with
earlier versions, it becomes increasingly difficult to find the reliable
commandline versions that work well on all platforms. Therefore I have
placed the source of PGP 2.6.3ia here. Unix users
should unpack it with unzip -a to convert the end of lines
correctly. A project file for MS Visual Studio 5
to compile a native win32 version using long filenames is also available.

A special development line of PGP that aimes at solving some of the compatibility
problems that arise between the different versions are the "ui" versions. They
can be found at Steve
Crompton's homepage.

9.3 Gnu Privacy Guard

Another interesting development is the GNU
Privacy Guard. This program, although not fully compatible with PGP 2.x (it
does not create pgp 2.x compatible keys (version 3 or V3 keys) but it can use
existing V3 keys).

Signal is a chat and VOIP app for Android and iOS for secure, private comunication.
I like it a lot but I'm not pleased with the existing backup functionality on Android: the old method was incomplete
and the current one is too slow and buggy, so I forked the source and implemented my own backup. Source, patches
for the original source code and installable apk files can be found at
Github.